The Keencyclopedia
Let you open doors. Unlike the gems in keen the other keens, the keys in Keen Dreams stay with you when you die, unless you use them from level to level and can be used on any door. For Keen GBC, the keys are distributed throughout the level and are important to completing the level, but are also color coded.
Found in: Keen Dreams, Keen GBC

Keen Dreams

Keen GBC